Date of Award

2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Natural Resources

First Advisor

Anthony W. D'Amato

Abstract

Northern hardwood forests are a vast, temperate forest-type existing across much of northeastern North America. In the northeastern U.S., these forests are found from New York to Maine where they have central cultural, ecological, and economic significance. These ecosystems are incredibly variable across this region, growing on a range of sites and influenced by a suite of biotic and abiotic conditions. Developing management regimes that accommodate the ecological complexity of these forests has been the focus of silvicultural studies for decades; however, this work has been constrained by temporal and spatial limitations. As such, there is still uncertainty regarding the evolution and variability of northern hardwood forests over time and across sites under different management scenarios. To address this uncertainty we synthesized long-term silvicultural studies (20 years +) throughout the northeast and assessed outcomes as they related to management objectives and changing forest conditions. Specifically, we explored the regeneration dynamics and development of overstory conditions for even and uneven-aged systems with four distinct approaches. First, we established context for this work through review of existing silvicultural research and analysis of the current northern hardwood resource. Next, we applied long-term, regional inventories to consider abiotic and biotic factors influencing recent sugar maple (Acer saccharum) establishment and survival. We then evaluated long-term outcomes of commonly applied even and uneven-age silvicultural systems across a range of sites in New York and New Hampshire using repeated inventories from long-term research trials. Finally, we followed the evolution of gap dynamics over eight decades in the oldest group selection study in North America; research established at the Bartlett Experimental Forest in New Hampshire in the early 1930s. Cumulatively, results showed a frequent disconnect between structure and composition of the overstory and regeneration layers, and the potential for future challenges to sustaining current overstory species. In addition, this work highlighted the pervasive, negative influence of American beech (Fagus grandifolia) across the region on regeneration of desired species, namely sugar maple and yellow birch (Betula alleghenesis). Outcomes from this work suggest that a variety of silvicultural systems can be used to maintain and regenerate northern hardwood forests; however favorable outcomes require careful consideration of site conditions with management regimes tailored accordingly.

Language

en

Number of Pages

258 p.

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